The present invention relates to an electrically powered motor vehicle and, specifically, to a ram air driven turbine generator charging system for the vehicle that utilizes control of both turbine torque and electrical loading at the generator output to charge the vehicle battery and power the vehicle while minimizing the turbine caused drag resistance of the vehicle.
Prior art describes wind powered electric generator systems mounted on the roof, the hood or internal to an electric vehicle to charge the vehicle battery while the vehicle is in motion (Guenard, 2002/0066608, 2002; Deets, U.S. Pat. No. 7,135,786, 2006; Maberry, U.S. Pat. No. 7,147,069, 2006; Burns, U.S. Pat. No. 5,760,515, 1998, for example). The prior art also describes air flow management systems including both fixed and variable shroud configurations purported to control or eliminate drag resistance associated with turbine systems. The many embodiments in prior art do not consider adequately the fundamental issues inherent in converting and storing the ram air kinetic energy developed by a vehicle in motion, that is, (a) the ram air energy necessary to cause the turbine generator to rotate manifests as additional vehicle drag which, if vehicle speed is to be maintained, must be overcome by the application of additional traction drive energy and; (b) as the vehicle battery approaches full charge, the increased electrical load on the generator increases which increases the torque load on the turbine, adding to the turbine caused drag resistance. Prior art devices to control battery charge resistance affect on generator load are effective but slow acting and not efficient. The two effects are limiting in any attempt to achieve a functionally useable result in converting and storing the ram air energy of a moving electric vehicle that, in normal use, operates in a wide range of speeds and battery charge levels. It is necessary for the charging system to be effective and efficient at both low and high speeds over a range of battery charge levels. The present embodiment resolves these issues and thereby extends significantly the driving range of an electric vehicle between times that it becomes necessary to charge the vehicle by external means.
What is needed in the art is an electric vehicle, including at least one ram air driven turbine generator and at least one ultra capacitor auxiliary energy storage device, that controls turbine generator caused drag by managing turbine generator torque and battery charge resistance. This will provide for sufficient battery charging energy and vehicle power to extend the driving range of the vehicle between external battery charges.